InGaSb MOSFET Channel on Metamorphic Buffer: Materials, Interfaces and Process Options

摘要

High quality bulk GaSb and InGaSb quantum wells grown on GaAs substrates were MBE grown using a AlGaSb(As) metamorphic buffer layers to reduce dislocation density down to 10~7cm~(-2). Strained In_(0.36)Ga_(0.64)Sb quantum wells with a biaxial compressive strain of 1.8% showed the highest mobility of 1020 cm~2/Vs and a low sheet resistance of 3.9 kΩ/sq. at hole sheet at hole density of 1.9×10~(12) cm~(-2) Buried channel design with an AlGaSb top barrier improved hole mobility by only 30% compared to surface QW channels. Improving the interface trap density down to 10~(12) cm~(-2)eV~(-1) was realized using an amorphous Si layer (in-situ gate oxide) or an InAs layer (ex-situ gate) as a gate passivation. p~(++)-GaSb epitaxial contact layers were developed and showed the leakage current of ～0.1 mA/cm~2 not affected by growth defects. Critical elements of "gate-last" InGaSb MOSFET fabrication process were developed utilizing an InAs etch stop layer to avoid high temperature processing of the gate stack.